Endo-BCN-PEG-t-butyl ester is a compound that belongs to the class of polyethylene glycol (PEG) derivatives. This compound is designed to contain functional groups, which makes it useful for various applications in pharmaceutical research and development. The functional groups present in Endo-BCN-PEG-t-butyl ester are capable of participating in chemical reactions that are essential for the modification of drug molecules. In particular, the compound is used for the labeling of biomolecules, drug conjugation, and for the preparation of drug delivery systems. The introduction of Endo-BCN-PEG-t-butyl ester has thus provided a valuable tool for researchers in the pharmaceutical industry, enabling them to develop new drugs and therapies that are more effective and targeted towards specific diseases.